1. Field of the Invention
The present invention relates to a zoom finder of a real image type and a real image type zoom finder capable of making a magnification transition. The present invention can be utilized in a finder for a 35 mm lens shutter camera, a video camera and an electronic still camera.
2. Description of the Related Art
In a desirable zoom finder of a real image type, an entire length of the zoom finder is short and the structure of a mechanical mechanism for displacing lenses in a zooming operation is simplified and no diopter is changed in the zooming operation.
The following Japanese Patent Applications show general zoom finders of a real image type in which the entire length of the zoom finder is short and is not changed in the zooming operation. In Japanese Patent Application Laying Open (KOKAI) No. 2-191908, an objective lens is constructed by a first lens group having positive refracting power, a second lens group having negative refracting power and a third lens group having positive refracting power. A magnification of this zoom finder is increased by displacing the second lens group from an object side to an eyepiece side. In Japanese Patent Application Laying Open (KOKAI) No. 2-173713, an objective lens is constructed by a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power and a fourth lens group having small refracting power. A zooming operation of this zoom finder is performed by moving the second and third lens groups while a diopter of the zoom finder is constantly held. In Japanese Patent Application Laying Open (KOKAI) No. 2-173714, an objective lens is constructed by a first lens group having positive refracting power, a second lens group having negative refracting power and a third lens group having positive refracting power. A zooming operation of this zoom finder is performed by moving the second and third lens groups while a diopter of the zoom finder is constantly held. In the first zoom finder of the Japanese Patent Application Laying Open (KOKAI) No. 2-191908, the diopter of the zoom finder is changed in the zooming operation. In the Japanese Patent Application Laying Open (KOKAI) Nos. 2-173718 and 173714, a moving amount of the third lens group is increased to perform the zooming operation so that it is necessary to dispose a space for moving the third lens group and a mechanism for moving the third lens group.